Bring a large pot of salted water to a boil over medium-high heat. Cook the penne to al dente, according to the time on the package directions. Before draining the pasta, reserve 1 cup of starchy pasta water. 

Heat a large high-sided skillet over medium heat. Add the olive oil, shallot, and garlic. Cook for 2-3 minutes, or until the shallot is tender. 

Next add the butter, lemon juice, and red pepper flakes (if using). Stir until the butter has melted. 

Add ½ cup of the starchy pasta water and stir for 1-2 minutes, or until the sauce begins to bubble and thicken. Add the sun-dried tomatoes, kale, and penne. Toss to combine. 

If the sauce is too thin, add another ¼ cup of the reserved pasta water. Continue to cook the pasta for 1-2 minutes, or until the kale is just barely wilted and the sauce evenly coats the pasta. Again, if the sauce becomes too dry add the last ¼ cup of pasta water. 

Remove the pan from the heat and add the parmesan. Stir to combine and season with salt and pepper to taste.